[charleyahrens]

My 81 feels as if it is having carb problems when driving in city traffic when the outside temperature is over 100. There does not appear any cooling system issues as it has never overheated. Does this sound like a carb spacer may be needed? The engine is stock with no mods. New plugs - wires and cap have been installed. Any help would be appreciated.

 

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did you find the problem on hot days ? was it fuel boiling ? EGR Valve? Ignition module?

 

[charleyahrens]

I believe that it may well be that the fuel is boiling as the symptom only surfaces when the outside temperature is over 100 degrees and I am in slow moving traffic.. Once it starts to "stumble", it is hard to restart if it stalls out. Other than that, it runs without any issues. It idles smoothly, no hesitation on acceleration and and starts up right away. I am thinking about installing intake manifold gaskets with the heat passage blocked. Do you have any alternative suggestions?

 

[toobroketoretire]

I believe that it may well be that the fuel is boiling as the symptom only surfaces when the outside temperature is over 100 degrees and I am in slow moving traffic.. Once it starts to "stumble", it is hard to restart if it stalls out. Other than that, it runs without any issues. It idles smoothly, no hesitation on acceleration and and starts up right away. I am thinking about installing intake manifold gaskets with the heat passage blocked. Do you have any alternative suggestions?

If it's just a case of boiling fuel you can easily solve the problem by slipping a piece of .010" stainless steel shim stock between the intake gasket and the exhaust holes in the heads (yes, you have to take the intake manifold off to do this). Brass shim stock will also work but stainless steel is burn-proof..................

 

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toobrokes right, if it is boiling fuel, block that heat riser passage and put a phenolic spacer under the carb .. it will stop

 

[charleyahrens]

Thanks for the info. Two questions, is using a shim preferable to using a specialty gasket and what spacer thickness is recommended?

 

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either way.. just block the heat... the spacers are 1/4 inch and up.. it doesn t take a thick spacer to control the heat transfer. Those of us in hot climates have to deal with high underhood temps.

 

[7t9l82]

i agree 100% block that riser and at least a thick gasket or a phenolic spacer.